Develop Reference

android ViewPager starts at a wrong random location after reload

I am writing a simple view pager test app that loads a bunch of data from a website and creates pages to display them.
For the most part the displaying is pretty much all works. However, it falls apart when I load a new set of data to display. When I get a new set, it loads all the data perfectly well however, instead of starting from view 0 it starts at a random location. It could start at the end or somewhere in the middle.
I want all the data to load from page 1, like a book. If you load a new book the book should start from page 1 not a random page.
Reloading calls
I've tried using GotCampDetails() which sets the local variable in the class.
viewPager.setCurrentItem(0);
in my fragment but it doesn't work. Also called notifydatasetchanged() on my adapter, still didn't work.
What am I missing?
public class ViewPagerFragment extends Fragment implements WebReadResultsListener {
private ArrayList<HashMap<String, String>> campDetails;
CustomPagerAdapter adapter;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.camp_viewpager, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
if (campDetails != null && ! campDetails.isEmpty()) {
ViewPager viewPager = (ViewPager) view.findViewById(R.id.viewpager);
adapter = new CustomPagerAdapter(getActivity(), campDetails, viewPager);
viewPager.setAdapter(adapter);
viewPager.setPageTransformer(true, new ZoomOutPageTransformer());
}
}
#Override
public boolean GotCampDetails(ArrayList<HashMap<String, String>> campDetails) {
this.campDetails = campDetails;
return true;
}
#Override
public boolean GotCampList(ArrayList<HashMap<String, String>> campDetails) {
return false;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
getFragmentManager().putFragment(outState,"fragmentInstanceSaved",getFragmentManager().findFragmentById(R.id.content));
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Handle orientation changes here
}
}
Adapter:
public class CustomPagerAdapter extends PagerAdapter implements ColorChangeListener {
private ArrayList<HashMap<String, String>> campDetails;
private ViewGroup collection;
private Context mContext;
private boolean isRunning = false;
private ColorChangeListener colorChangeListener;
private int color= pink;
private int currentposition;
private ViewPager viewPager;
public CustomPagerAdapter(Context context, final ArrayList<HashMap<String, String>> campDetails, ViewPager viewPager) {
this.campDetails=campDetails;
this.mContext = context;
this.viewPager = viewPager;
colorChangeListener = (ColorChangeListener) mContext;
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int pos) {
currentposition = pos;
if (campDetails.get(currentposition).get("color").equals("green")) {
color = green;
} else {
color = pink;
}
ColorAppBar(color);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
#Override
public Object instantiateItem(ViewGroup collection, final int position) {
LayoutInflater inflater = LayoutInflater.from(mContext);
ViewGroup layout = (ViewGroup) inflater.inflate(R.layout.child_item, collection, false);
if (campDetails.size() <= 0) {
Toast.makeText(mContext, "Error in getting camp details", Toast.LENGTH_SHORT).show();
return null;
}
if (campDetails.get(position).get("description").equals("RD") ) {
layout.setBackgroundColor(mContext.getResources().getColor(green));
} else {
layout.setBackgroundColor(mContext.getResources().getColor(pink));
}
collection.addView(layout);
this.collection = collection;
TextView eName = (TextView) layout.findViewById(R.id.en);
TextView nEName= (TextView) layout.findViewById(R.id.nen);
TextView textView6 = (TextView) layout.findViewById(R.id.textView6);
// ImageView nextImg = (ImageView) groupLayout.get(index).findViewById(R.id.nextImg);
eName.setText(campDetails.get(position).get("name"));
if (position+1 < campDetails.size()) {
nEName.setText(campDetails.get(position+1).get("name"));
textView6.setVisibility(View.VISIBLE);
} else {
nEName.setText("You are DONE!!");
textView6.setVisibility(View.INVISIBLE);
}
return layout;
}
#Override
public void destroyItem(ViewGroup collection, int position, Object view) {
collection.removeView((View) view);
}
#Override
public int getCount() {
return campDetails.size();
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#Override
public CharSequence getPageTitle(int position) {
return campDetails.get(position).get("name");
}
#Override
public void ColorAppBar(int color) {
colorChangeListener.ColorAppBar(color);
}
}

I finally managed to get it done.
I had to delay the function call setCurrentItem by a few milliseconds. Race condition? I don't know why this is the case but now it works perfectly.
Here is what I added in case someone else may find it useful:
pager.postDelayed(new Runnable() {
#Override
public void run() {
pager.setCurrentItem(pos);
}
}, 100);

I'm having trouble following the details well enough to pinpoint the problem, but this guy seems to have accomplished what you're trying to do: dynamically add and remove view to viewpager
hope it helps

Is it possible to know which image display in ViewPager?

I have two images. I used ViewPager to display them individually. I want to know which ones is displaying in the screen. Could you help me to solve it? For example, when I scroll the screen, the first image will display and Toast a message such as "This is first image", do same thing for second image. Thanks in advance. This is my code
public class ViewPagerExample extends FragmentActivity{
private MyAdapter mAdapter;
private ViewPager mPager;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mAdapter = new MyAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(mAdapter);
}
public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return 2;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
{
return new ImageFragment(R.drawable.image1);
}
case 1:
{
return new ImageFragment(R.drawable.image2);
}
default:
return null;
}
}
}
}
and the ImageFragment class
public class ImageFragment extends Fragment {
private final int imageResourceId;
public ImageFragment(int imageResourceId) {
this.imageResourceId = imageResourceId;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.e("Test", "hello");
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.image_layout, container, false);
ImageView imageView = (ImageView) view.findViewById(R.id.imageView1);
imageView.setImageResource(imageResourceId);
return view;
}
}

try something like this
mPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int pager_position) {
// show toast here for images
}
#Override
public void onPageScrollStateChanged(int state) {
}
});

You can use these lines of code to detect the image on swipe
ViewPager.SimpleOnPageChangeListener pageChangeListener = new ViewPager.SimpleOnPageChangeListener(){
#Override
public void onPageSelected(int position) {
super.onPageSelected(position);
System.out.println("Positoin is the=="+position);
if(position==0)
{
///on the zero position you can get the image
}
else
{
///on the first position you can get the image
}
}
};

There is a method yourViewpagerObject.getCurrentItem() which returns the position of currently Viewed page of view pager

Android 5.0(lollipop) - The event function is shown in logcat by calling program but the screen does not move

Development environment
android phone version : 5.0(lollipop)
development tool : ADT(Build : v22.0.0-675183)
my app's minSdkVersion : API13
Problem Description
I use the slide menu library(open source : github.com/jfeinstein10/SlidingMenu).
The main layout consists of a [ListView] with [ViewPager] and [Left Slide Menu].
Before I open the left slide menu, it functions manually.
However, a scroll of listview and a swipe event in viewpager do not operate well after opening the left slide menu.
To expatiate on this, the event function is shown in logcat by calling program but the screen does not move.
Please answer if you know it.
My Code
public class AndroidTestActivity extends FlagmentActivity implements OnPageChangeListener, OnClickListener {
private ListView listView;
private ViewPager mPager;
private SlidingMenu menu;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
listView = (ListView) findViewById(R.id.list);
mAdapter = new MainListAdapter(this);
listView.setAdapter(mAdapter);
listView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
...
}
});
mPager = (ViewPager)findViewById(R.id.pager);
mPager.setAdapter(new MyPagerAdapter(getApplicationContext()));
menu = new SlidingMenu(this);
menu.setTouchModeAbove(SlidingMenu.TOUCHMODE_MARGIN);
menu.setShadowWidthRes(R.dimen.shadow_width);
menu.setShadowDrawable(R.drawable.shadow);
menu.setBehindOffsetRes(R.dimen.slidingmenu_offset);
menu.setFadeDegree(0.15f);
menu.attachToActivity(this, SlidingMenu.SLIDING_CONTENT);
menu.setMenu(R.layout.menu_frame);
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.menu_frame, new LeftSlideMenuListFragment(MainMenuActivity.this))
.commit();
}
private class MyPagerAdapter extends PagerAdapter {
private LayoutInflater mInflater;
public MyPagerAdapter(Context context) {
super();
mInflater = LayoutInflater.from(context);
}
#Override
public int getCount() {
return 2;
}
#Override
public Object instantiateItem(View pager, int position) {
View v = null;
if(position==0) {
v = mInflater.inflate(R.layout.main_menu_01, null);
...
} else if(position==1) {
v = mInflater.inflate(R.layout.main_menu_02, null);
...
}
((ViewPager)pager).addView(v, 0);
return v;
}
#Override
public void destroyItem(View pager, int position, Object view) {
((ViewPager)pager).removeView((View)view);
}
#Override
public boolean isViewFromObject(View view, Object obj) {
return view == obj;
}
#Override public void finishUpdate(View arg0) { }
#Override public void restoreState(Parcelable arg0, ClassLoader arg1) {}
#Override public Parcelable saveState() { return null; }
#Override public void startUpdate(View arg0) {}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
}
#Override
public void onPageScrollStateChanged(int arg0) {}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {}
#Override
public void onPageSelected(int position) {}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
if(menu.isMenuShowing()) {
menu.showContent();
mPager.getAdapter().notifyDataSetChanged();
mPager.invalidate();
} else {
finish();
}
}
return false;
}
}

Does PullToRefresh work with FragmentPagerAdapter?

Libraries:
https://github.com/chrisbanes/Android-PullToRefresh
https://github.com/JakeWharton/Android-ViewPagerIndicator
In the Sample PullToRefreshListInViewPagerActivity only works with PageAdapter.
I couldn't find a way to put it to work with FragmentPageAdapter.
Sample:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_ptr_list_in_vp);
mViewPager = (ViewPager) findViewById(R.id.vp_list);
mViewPager.setAdapter(new ListViewPagerAdapter());
}
private class ListViewPagerAdapter extends PagerAdapter {
#Override
public View instantiateItem(ViewGroup container, int position) {
Context context = container.getContext();
PullToRefreshListView plv = (PullToRefreshListView) LayoutInflater.from(context).inflate(
R.layout.layout_listview_in_viewpager, container, false);
ListAdapter adapter = new ArrayAdapter<String>(context, android.R.layout.simple_list_item_1,
Arrays.asList(STRINGS));
plv.setAdapter(adapter);
plv.setOnRefreshListener(PullToRefreshListInViewPagerActivity.this);
// Now just add ListView to ViewPager and return it
container.addView(plv, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
return plv;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#Override
public int getCount() {
return 3;
}
}
#Override
public void onRefresh(PullToRefreshBase<ListView> refreshView) {
new GetDataTask(refreshView).execute();
}
private static class GetDataTask extends AsyncTask<Void, Void, Void> {
PullToRefreshBase<?> mRefreshedView;
public GetDataTask(PullToRefreshBase<?> refreshedView) {
mRefreshedView = refreshedView;
}
#Override
protected Void doInBackground(Void... params) {
// Simulates a background job.
try {
Thread.sleep(4000);
} catch (InterruptedException e) {
}
return null;
}
#Override
protected void onPostExecute(Void result) {
mRefreshedView.onRefreshComplete();
super.onPostExecute(result);
}
}
}

You can add a ListFragment to the FragmentPageAdapter (or FragmentStatePageAdapter) and add the Pull-To-Refresh feature on it.
The Android-PullToRefresh repository has an example about ListFragment.
The Android Developers website has a sample code on how to make FragmentPagerAdapter or FragmentStatePagerAdapter.
You can also take a look at my test project: https://github.com/caiguanhao/FSPAtest

How to force ViewPager to re-instantiate its items [duplicate]

This question already has answers here:
Why `PagerAdapter::notifyDataSetChanged` is not updating the View?
(43 answers)
Closed 10 years ago.
I am using ViewPager to allow user to swipe between its views. Is there a way how to force this ViewPager to reload/re-instantiate its views in case that they are no longer valid or needs to be refreshed? I tried to call notifyDataSetChanged() on its adapter but this does not invoke instantiateItem() method again.
EDIT
Here is the class that extends from ViewPager and its adapter definision. Bellow is the refresh() method that I call when I want to force to refresh items.
public class DayFlipper extends ViewPager {
public class FlipperAdapter extends PagerAdapter {
#Override
public int getCount() {
return DayFlipper.DAY_HISTORY;
}
#Override
public void startUpdate(View container) {
}
#Override
public Object instantiateItem(View container, int position) {
Log.d(TAG, "instantiateItem(): " + position);
Date d = DateHelper.getBot();
for (int i = 0; i < position; i++) {
d = DateHelper.getTomorrow(d);
}
d = DateHelper.normalize(d);
CubbiesView cv = new CubbiesView(mContext);
cv.setLifeDate(d);
((ViewPager) container).addView(cv, 0);
// add map
cv.setCubbieMap(mMap);
cv.initEntries(d);
return cv;
}
#Override
public void destroyItem(View container, int position, Object object) {
((ViewPager) container).removeView((CubbiesView) object);
}
#Override
public void finishUpdate(View container) {
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == ((CubbiesView) object);
}
#Override
public Parcelable saveState() {
return null;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
}
}
...
public void refresh() {
getAdapter().notifyDataSetChanged();
}
}

Had the same problem. For me it worked to call
viewPage.setAdapter( adapter );
again which caused reinstantiating the pages again.

I have found a solution. It is just a workaround to my problem but currently the only solution.
ViewPager PagerAdapter not updating the View
public int getItemPosition(Object object) {
return POSITION_NONE;
}
Does anyone know whether this is a bug or not?

public class DayFlipper extends ViewPager {
private Flipperadapter adapter;
public class FlipperAdapter extends PagerAdapter {
#Override
public int getCount() {
return DayFlipper.DAY_HISTORY;
}
#Override
public void startUpdate(View container) {
}
#Override
public Object instantiateItem(View container, int position) {
Log.d(TAG, "instantiateItem(): " + position);
Date d = DateHelper.getBot();
for (int i = 0; i < position; i++) {
d = DateHelper.getTomorrow(d);
}
d = DateHelper.normalize(d);
CubbiesView cv = new CubbiesView(mContext);
cv.setLifeDate(d);
((ViewPager) container).addView(cv, 0);
// add map
cv.setCubbieMap(mMap);
cv.initEntries(d);
adpter = FlipperAdapter.this;
return cv;
}
#Override
public void destroyItem(View container, int position, Object object) {
((ViewPager) container).removeView((CubbiesView) object);
}
#Override
public void finishUpdate(View container) {
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == ((CubbiesView) object);
}
#Override
public Parcelable saveState() {
return null;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
}
}
...
public void refresh() {
adapter().notifyDataSetChanged();
}
}
try this.